How Elysia the sea slug makes her own solar snacks

The incredible Elysia chlorotica sucks up plastids from algae to be able to photosynthesize
Elysia chlorotica This unassuming little sea slug named Elysia says she can use sunlight to make her own food, the same way that plants do. (Karen N. Pelletreau et al/Wikimedia Commons)

One of the first things that we learn about in biology is the incredible superpower possessed by all plants and algae. Photosynthesis.

Give plants some sun and water (as well the carbon dioxide in our atmosphere) and presto! These amazing lifeforms make their own food, growing all by themselves.

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(Getty Embed)

In a lot of ways, this ability is the backbone of all life on Earth. Plants and algae are at the base of all food chains—without their ability to photosynthesize, they can't grow, and animals that depend on them for food go hungry. And did we mention the fact that the waste product from photosynthesis—oxygen—sort of comes in handy, too?

Honestly, the only way that animals could get around their need for plants and algae would be if they could photosynthesize, too. And, as we all know, that's just impossi ...


Wait, was that our phone?


We're sorry, excuse us a second ... Hello, OWLconnected Hotline. Pardon, you're a what? A sea slug? And your name is Elysia? Okay, Elysia, pleased to meet you—how can we ... what? You say that you can ... photosynthesize?! Hold on, stay on the line...

Solar-powered sea slugs?

Okay folks, this post just took an interesting turn! We're on the line with a sea slug named Elysia chlorotic, or Elysia for short. She says that she has the power of photosynthesis! That's quite an exceptional claim, so let's investigate.

Okay, Elysia emailed a recent selfie for us. She says this is her, eating her favourite snack, algae ...

elysia sea slug

(Karen N. Pelletreau/University of Maine)

Hey there, Elysia! You said that you made your own food? What's that? REALLY?

She says that she isn't actually eating the algae in this picture. She is sucking up its ... algal plastids? Let's break this down.

The plastids are what allow the algae to photosynthesize. Elysia here doesn't digest the plastids. Instead, she says that she stores them by the millions inside her body and uses them later to turn sunlight and water into her own food, just like a plant would. She says it's also the secret to keeping her skin a radiant green colour.

And look here, she sent us some papers from scientists at Rutgers University-New Brunswick. A professor named Debashish Bhattacharya totally backs up Elysia's story here. Just amazing!

Wow, Elysia. Thanks so much for your call. It's not everyday that we get to talk to a real-life solar-powered animal!

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